Crystalline mixture solid containing maltitol and preparation therefor

ABSTRACT

A crystalline mixture solid containing maltitol having an oil absorptivity of 0.1 to 6.9 wt % and a bulk density of 0.60 to 0.75 g/cc when it is ground and classified to ensure that at least 70 wt % of the obtained particles should have a particle size of 16 to 50 mesh and a process for producing a crystalline mixture solid containing maltitol, comprising introducing air bubbles into a maltitol aqueous solution. According to this process, a crystalline mixture solid containing maltitol having high solubility and almost no moisture absorption is produced at a high work efficiency and a low cost in a short period of time.

FIELD OF THE INVENTION

The present invention relates to a crystalline mixture solid containingmaltitol and to a production process therefor.

PRIOR ART

Since maltitol is hardly digested and absorbed in a digestive organ andrarely fermented by oral bacteria, it is used in low-calorie foods, dietfoods, little cariogenic foods and sweetening agents for diabetics andthe like. However, as a maltitol dried product is remarkably moistureabsorptive, deliquescent and hardly powdered, it is very difficult tohandle.

To solve this problem, there have been proposed many technologies forcrystallizing or powdering maltitol. For example, JP-B 3-7349 (the term“JP-B” as used herein means an “examined Japanese patent publication”)proposes a technology for commercializing maltitol by adjusting thewater content of a high-concentration maltitol solution to 2 to 15 wt %,adding a seed crystal to this solution, gradually cooling the resultingsolution to solidify maltitol, roughly grinding this solidified productas required, drying and grinding it to a desired particle diameter. Inthis technology, a 70% aqueous solution of maltitol is concentrated to awater content of 10%, maltitol powders are added to this concentratedsolution, and the resulting solution is cooled from 90° C. to normaltemperature in about 20 hours to be solidified.

JP-B 1-47140 discloses a technology for obtaining granular maltitol byplacing a concentrated solution of reduced maltose in a tray, adding acrystal, fully kneading and keeping warm the resulting solution topromote crystallization in order to obtain plasticity, extruding theproduct from pores, cooling and cutting the extruded product with anedged tool.

JP-B 7-14953 discloses a process for producing a crystalline mixturesolid containing maltitol by continuously supplying a maltitol aqueoussolution into an extruder having a slender cooling/kneading zone,cooling and kneading it in the presence of a seed crystal to form amaltitol magma, and continuously extruding it from an extrusion nozzle.

The above processes which make use of a seed crystal are now mainly usedto produce a crystalline mixture solid containing maltitol because ofthe production ease of a crystalline mixture solid containing maltitol.However, as the amount of a seed crystal added must be increased toimprove the production speed and part of the produced crystallinemixture solid containing maltitol is recycled in the productionprocesses which make use of the seed crystal, the processes involve sucha problem that the production efficiency is low.

Meanwhile, JP-B 2-11599 and JP-A 61-180795 (the term “JP-A” as usedherein means an “unexamined published Japanese patent application”), forexample, propose another production process in which maltitol isproduced by hydrogenating maltose, its purity is increased bychromatography and maltitol crystals are separated from thisconcentrated solution.

JP-A 6-234786 discloses a process for continuously producing a maltitolslurry by continuously introducing a maltitol aqueous solution into avessel and stirring.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a novel crystallinemixture solid containing maltitol which has eliminated the abovephysical problems of prior art maltitol.

It is another object of the present invention to provide a novelcrystalline mixture solid containing maltitol which has high solubilityand almost no moisture absorption.

It is still another object of the present invention to provide a processfor producing the crystalline mixture solid containing maltitol of thepresent invention, which has improved production efficiency.

It is a further object of the present invention to provide a process forproducing a crystalline mixture solid containing maltitol, which iscapable of producing a crystalline mixture solid containing maltitol ata high work efficiency and a low cost in a short period of time.

Other objects and advantages of the present invention will becomeapparent from the following description.

According to the present invention, firstly, the above objects andadvantages of the present invention are attained by a crystallinemixture solid containing maltitol which has an oil absorptivity of 0.1to 6.9 wt % and a bulk density of 0.60 to 0.85 g/cc when it is groundand classified to ensure that at least 70 wt % of the obtained particlesshould have a particle size of 16 to 50 mesh.

Secondly, the above objects and advantages of the present invention areattained by a process for producing a crystalline mixture solidcontaining maltitol, comprising dispersing air bubbles in a maltitolaqueous solution, supplying the resulting aqueous solution into akneader to form a plastic mass and grinding the mass (may be referred toas “first production process” hereinafter).

Thirdly, the above objects and advantages of the present invention areattained by a process for producing a crystalline mixture solidcontaining maltitol, comprising continuously supplying a maltitolaqueous solution containing air bubbles dispersed therein into anextruder having a slender kneading/cooling zone to knead and cool it toform a maltitol magma and continuously extruding the magma (may bereferred to as “second production process” hereinafter).

In the fourth place, the above objects and advantages of the presentinvention are attained by a process for producing a crystalline mixturesolid containing maltitol, comprising supplying a maltitol aqueoussolution into a kneader, kneading while air is contained in the solutionto disperse air bubbles, keeping kneading and cooling the resultingsolution to form a plastic mass and grinding the mass (may be referredto as “third production process” hereinafter).

Finally, the above objects and advantages of the present invention areattained by a process for producing a crystalline mixture solidcontaining maltitol, comprising continuously supplying a maltitolaqueous solution into an extruder having a slender cooling/kneadingzone, kneading while air is contained in the solution to disperse airbubbles, keeping kneading and cooling the resulting solution to form amaltitol magma and continuously extruding the magma (may be referred toas “fourth production process” hereinafter).

The present invention will be described in detail hereinbelow.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The crystalline mixture solid containing maltitol of the presentinvention has an oil absorptivity of 0.1 to 6.9 wt % and a bulk densityof 0.60 to 0.85 g/cc when it is ground and classified to ensure that atleast 70 wt % of the obtained particles should have a particle size of16 to 50 mesh.

The oil absorptivity when at least 70 wt % of the particles have aparticle size of 16 to 50 mesh is 0.1 to 6.9 wt %, preferably 0.5 to 4.9wt % more preferably 2.0 to 4.9 wt %.

The bulk density when at least 70 wt % of the particles have a particlesize of 16 to 50 mesh is preferably 0.60 to 0.85 g/cc. The maltitolcontent of the crystalline mixture solid containing maltitol of thepresent invention is preferably 80 to 99 wt %.

The crystalline mixture solid containing maltitol of the presentinvention has the above characteristic properties and is thereforeexcellent in solubility. In spite of this, it has almost no moistureabsorption.

The crystalline mixture solid containing maltitol of the presentinvention is produced by dispersing air bubbles in a maltitol aqueoussolution and supplying the resulting solution into a kneader to kneadand cool it according to the first production process, or by supplying amaltitol aqueous solution into a kneader, kneading while air iscontained in the solution in the kneader to disperse air bubbles andknead and cool the resulting solution at the same time according to thethird production process.

That is, the gist of the present invention is to crystallize maltitol byproviding shear force to the maltitol aqueous solution in the presenceof air bubbles.

The above maltitol aqueous solution as the starting material preferablyhas a solid content of 85 to 99 wt %, preferably 90 to 99 wt % and amaltitol purity of 80 wt % or more, preferably 80 to 99 wt %, morepreferably 85 to 99 wt %. The above maltitol aqueous solution as thestarting material contains substantially no maltitol crystals.

In the first production process, to disperse air bubbles in the maltitolaqueous solution, a commonly used stirrer may be used to stir theaqueous solution. At this point, it is preferred to stir the aqueoussolution by supplying air into the aqueous solution from a vent pipesuch as a sparger from an air generator such as a compressor. The thusprepared maltitol aqueous solution contains air bubbles in an amount of0.5 to 20 cc, more preferably 1 to 9 cc based on 100 g of the aqueoussolution. The air bubbles are preferably as big as 0.5 to 200 μm, morepreferably 1 to 100 μm. Since the air bubbles are thus dispersed, thestirring time and stirring speed of the aqueous solution differaccording to the concentration and temperature of the aqueous solutionand the type of the stirrer. For example, when a 95% aqueous solution ofmaltitol having a temperature of 110° C. is to be stirred using ahigh-speed homomixer (Type-M of Tokushu Kiki Kogyo Co., Ltd.), it may bestirred at a stirring speed of 8,000 rpm for about 2 minutes. At thispoint, air bubbles are fully dispersed in the maltitol aqueous solution.

The thus obtained maltitol aqueous solution containing air bubbles fullydispersed therein is supplied into a kneader and preferably pressurizedto provide shear force in order to prevent the air bubbles fromsubstantially being removed from the aqueous solution, thereby producingthe crystalline mixture solid containing maltitol of the presentinvention in accordance with the first production process.

The temperature when the raw material is supplied into the kneader ispreferably about 50 to 110° C. in consideration of the fact that it iseasier to handle when its fluidity is higher and control ease for theformation of a magma.

According to the third production process, it is possible to produce thecrystalline mixture solid containing maltitol of the present inventionwithout dispersing air bubbles in the maltitol aqueous solution inadvance as described above. In this case, a sheer maltitol aqueoussolution is used as the raw material, supplied into the kneader andkneaded while air is contained in the solution in the kneader to includeand fully disperse air bubbles, and the resulting solution is kneadedand cooled to produce the crystalline mixture solid containing maltitolof the present invention. The preferred content and size of the airbubbles are the same as in the first production process.

The temperature when the raw material is supplied into the kneader ispreferably about 80 to 110° C. in consideration of inclusion ease anddispersion ease of air bubbles in the kneader.

The cooling portion for forming a plastic mass may be adjusted to atemperature at which the generated heat of crystallization can beremoved, preferably 90° C. or less, more preferably 50° C. or less.

Although the feed rate of the raw material differs according to the typeand capacity of the used kneader, it is preferably 2 to 50 kg/hr whenthe KRC kneader (2S) of Kurimoto, Ltd. is used.

The obtained crystalline mixture solid composition can be made powderyby grinding or granular by granulation. Methods for grinding andgranulation are not particularly limited and a commonly used grinder andgranulator may be used. The obtained powder or granule may be dried by acommonly used drying method or sifted as required. When it is dried,airborne drying, fluidized bed drying, vacuum drying and tray drying allof which are generally used may be employed.

In the second production process and the fourth production process, anextruder having a slender cooling/kneading zone is used.

The extruder is not limited to a particular type, for example, an openor closed type, or a batch or continuous type, if it can knead and coolat the same time. Preferably, it can extrude from an exhaust portcontinuously after kneading and cooling. Examples of the kneader includean extruder, continuous kneader, mixtron and kneadex. Out of these, anextruder is preferred. Examples of the extruder include the KRC kneader(of Kurimoto, Ltd.), double-screw extruder for foods (of Nippon SteelCo., Ltd.) and double-screw cooking extruder (of W & P Co., Ltd. ofGermany).

When the magma is to be extruded from a continuous type extruder, theshape of the magma may be arbitrary, for example noodle-like,ribbon-like, rod-like or plate-like shape. In consideration of thesubsequent steps such as cooling and grinding, it is preferably extrudedin a noodle-like or ribbon-like shape. A punching plate provided at theexhaust port preferably has a pore diameter of 2 to 5 mm and a porosityof 10 to 40%.

The cooling method is not particularly limited but the magma extrudedfrom the extruder may be directly exposed to cool air, left at roomtemperature or cooled to room temperature with cool air on a metal netbelt.

According to the above process, a powdery or granular crystallinemixture solid containing maltitol which does not require a drying step,is easy to handle, readily soluble and rarely moisture absorptive andhas high quality can be obtained at a low cost in a short period oftime.

The preparation method of the maltitol aqueous solution, the content andsize of the air bubbles and the grinding and granulation of the obtainedcrystalline mixture solid in the second and fourth production processesare the same as in the first and third production processes. As for whatare not described herein of the second and fourth production processes,it should be understood that the above descriptions of the first andthird production processes are applied to the second and fourthproduction processes directly or with modifications obvious to one ofordinary skill in the art.

The following examples and comparative examples are given to furtherillustrate the present invention.

EXAMPLES

The following physical property values in the examples were measured asfollows.

Oil Absorptivity (wt %)

15 g of a sample and an appropriate amount of castor oil were mixedtogether and left for 5 minutes, an oil fraction which was not retainedin the sample was removed by a centrifugal machine having a60M netstretched thereon (1300 G, 10 minutes), and the weight (A) of the samplecontaining the residual oil was measured. The oil absorptivity wascalculated from this value based on the following equation.oil absorptivity (wt %)=(A−15)/15×100Bulk Density (g/cc)

This was measured using the PT-N powder tester (Hosokawa Micron Co.,Ltd.) (180 times of tapping).

Melting Point (° C.)

The crystalline mixture solid containing maltitol was dried at normaltemperature under vacuum for 1 hour, placed in a sealed sample container(made from Ag, 15 μl) and measured for its melting point using adifferential scanning thermometer (DSC6200: Seiko Instruments Co., Ltd.)at a temperature range of 30 to 200° C. and a temperature elevation rateof 4° C./min.

Content (cc/100 g) and Size of Air Bubbles

The maltitol aqueous solution containing air bubbles dispersed thereinwas placed in a 100 ml female cylinder to measure its densityimmediately (volume/weight). At the same time, the density of a controlcontaining no air bubbles and having the same temperature was measured.The difference between the inverse numbers of the obtained values wastaken as the content of the air bubbles.

The size of the air bubbles was measured by the observation of amaltitol aqueous solution containing air bubbles dispersed thereinthrough a microscope at a magnification of ×450.

Example 1

A maltitol aqueous solution (maltitol purity=90 wt %, solid content=95wt %, 110° C.) containing air bubbles dispersed therein was prepared byhigh-speed stirring (8,000 rpm) with a homomixer (Type-M of Tokushu KikaKogyo Co., Ltd.) while air was blown into the aqueous solution. When 700g of this maltitol aqueous solution was injected into a 2-liter batchkneader (twin armed, 30 to 40 rpm, jacket temperature=90° C.) and keptstirred, a plastic mass (85° C. at this point) was formed in 16 minutesand became powdery in 24 minutes. The obtained powders were sifted toobtain powders having a particle size of 16 to 50 mesh which were thenused for the measurement of oil absorptivity, bulk density (apparentspecific gravity) and melting point. The results are shown in Table 1.

Comparative Example 1

140 g of a maltitol aqueous solution (maltitol purity=90 wt %, solidcontent=95 wt %, 116° C.) was placed in a 2-liter separable flask andkept in a bath heated at 90° C. while it was stirred at a low speed withtwo pitched puddles. However, maltitol crystals were not formed afterthe passage of 25 minutes (the temperature of the solution was 88° C.).

Example 2

A maltitol aqueous solution (purity of maltitol=90 wt %, solidcontent=90 wt %, 110° C.) into which air bubbles were continuouslydispersed by a line mixer (7-E line mixer of Tokushu Kika Kogyo Co.,Ltd.) was continuously supplied into a continuous kneader having aslender kneading/cooling zone (KRC kneader S-2 of Kurimoto, Ltd., 60rpm, jacket temperature=70° C.) at a rate of 5 kg/hr and kept kneadedand cooled. A noodle-like solid was discharged from a punching plate atthe outlet. This was cooled and ground to obtain a high-qualitycrystalline mixture solid containing maltitol.

Test Example

Air dispersion by the line mixer in Example 2 was carried out under thefollowing conditions. That is, the maltitol aqueous solution (120° C.)was stirred by the line mixer at 6,000 rpm while compressed air (about 2kg/cm³) was supplied into the aqueous solution by a compressor touniformly disperse air in the solution.

The amount of air in the maltitol aqueous solution containing airbubbles finely and uniformly dispersed therein was 1.2 cc/100 g. Whenthis solution was observed through a microscope and the sizes ofarbitrary 106 air bubbles were measured, the average size was 18.2 μm(standard deviation of 18.3 μm, maximum=69 μm, minimum=1.2 μm).

Example 3

A maltitol aqueous solution (maltitol purity=90 wt %, solid content=95wt %, 110° C.) was continuously supplied into a continuous kneaderhaving a slender kneading/cooling zone (KRC kneader S-2 of Kurimoto,Ltd., 60 rpm, jacket temperature=70° C.) at a rate of 5 kg/hr and airwas supplied into the kneader by a compressor at the same time to kneadthe solution by stirring with a kneader puddle while air was containedin the solution to disperse air bubbles and kept kneaded and cooled. Anoodle-like solid was discharged from a punching plate at the outlet.This was cooled and ground to obtain a high-quality crystalline mixturesolid containing maltitol. The obtained powders were sifted to obtainpowders having a particle size of 16 to 50 mesh which were then used forthe measurement of oil absorptivity, bulk density (apparent specificgravity) and melting point. The results are shown in Table 1.

When the inside of the kneader was observed in the course of operation,the kneaded product in the zone right after the supply of the rawmaterial solution contained fine air bubbles uniformly dispersed thereinby kneading with the kneader. When this was observed through amicroscope, the formation of maltitol crystals was not seen. Further,when the kneaded product in the subsequent zone was observed through amicroscope, maltitol crystals were observed.

Example 4

A maltitol aqueous solution (maltitol purity=88.3 wt %, solidcontent=97.7 wt %, 129° C.) was continuously supplied into a continuouskneader having a slender kneading/cooling zone (KRC kneader S-5 ofKurimoto, Ltd., 28 rpm, jacket temperature=10° C.) at a rate of 100kg/hr and air was supplied into the kneader by a compressor at the sametime to knead the solution by stirring with a kneader puddle while airwas contained in the solution to disperse air bubbles and kept kneadedand cooled. A noodle-like solid was discharged from a punching plate atthe outlet. This was cooled and ground to obtain a high-qualitycrystalline mixture solid containing maltitol. The obtained powders weresifted to obtain powders having a particle size of 16 to 50 mesh whichwas then used for the measurement of oil absorptivity, bulk density(apparent specific gravity) and melting point. The results are shown inTable 1.

TABLE 1 oil absorptivity bulk density melting point (%) (g/cc) (° C.)powder of 6.8 0.72 135 Example 1 powder of 2.7 0.75 137 Example 3 powderof 5.4 0.77 130 Example 4

1. A crystalline mixture solid containing maltitol having an oilabsorptivity of 0.1 to 6.9 wt % and a bulk density of 0.60 to 0.85 g/ccwhen it is ground and classified to ensure that at least 70 wt % of theobtained particles should have a particle size of 16 to 50 mesh.
 2. Thecrystalline mixture solid containing maltitol of claim 1 which has amaltitol content of 80 to 99 wt %.
 3. The crystalline mixture solidcontaining maltitol of claim 2 produced by a process comprisingdispersing air bubbles in a maltitol aqueous solution, supplying theresulting aqueous solution into a kneader to form a plastic mass andgrinding the mass.
 4. The crystalline mixture solid containing maltitolof claim 2 produced by a process comprising continuously supplying amaltitol aqueous solution containing air bubbles dispersed therein intoan extruder having a slender kneading/cooling zone to knead and cool itto form a maltitol magma and continuously extruding the magma.
 5. Thecrystalline mixture solid containing maltitol of claim 2 produced by aprocess comprising supplying a maltitol aqueous solution to a kneader,kneading while air is contained in the solution to disperse air bubbles,keeping kneading and cooling the resulting solution to form a plasticmass and grinding the mass.
 6. The crystalline mixture solid containingmaltitol of claim 2 produced by a process comprising continuouslysupplying a maltitol aqueous solution into an extruder having a slendercooling/kneading zone, kneading while air is contained in the solutionto disperse air bubbles, keeping kneading and cooling the resultingsolution to form a maltitol magma and continuously extruding the magma.7. The crystalline mixture solid containing maltitol of claim 1 producedby a process comprising dispersing air bubbles in a maltitol aqueoussolution, supplying the resulting aqueous solution into a kneader toform a plastic mass and grinding the mass.
 8. The crystalline mixturesolid containing maltitol of claim 1 produced by a process comprisingcontinuously supplying a maltitol aqueous solution containing airbubbles dispersed therein into an extruder having a slenderkneading/cooling zone to knead and cool it to form a maltitol magma andcontinuously extruding the magma.
 9. The crystalline mixture solidcontaining maltitol of claim 1 produced by a process comprisingsupplying a maltitol aqueous solution to a kneader, kneading while airis contained in the solution to disperse air bubbles, keeping kneadingand cooling the resulting solution to form a plastic mass and grindingthe mass.
 10. The crystalline mixture solid containing maltitol of claim1 produced by a process comprising continuously supplying a maltitolaqueous solution into an extruder having a slender cooling/kneadingzone, kneading while air is contained in the solution to disperse airbubbles, keeping kneading and cooling the resulting solution to form amaltitol magma and continuously extruding the magma.
 11. The crystallinemixture solid containing material of claim 1 which has an oilabsorptivity of 2.7 to 6.8 wt %.
 12. A process for producing acrystalline mixture solid containing maltitol, comprising dispersing airbubbles in a maltitol aqueous solution, supplying the resulting aqueoussolution into a kneader to form a plastic mass and grinding the mass.13. A process for producing a crystalline mixture solid containingmaltitol, comprising continuously supplying a maltitol aqueous solutioncontaining air bubbles dispersed therein into an extruder having aslender kneading/cooling zone to knead and cool it to form a maltitolmagma and continuously extruding the magma.
 14. A process for producinga crystalline mixture solid containing maltitol, comprising supplying amaltitol aqueous solution into a kneader, kneading while air iscontained in the solution to disperse air bubbles, keeping kneading andcooling the resulting solution to form a plastic mass and grinding themass.
 15. A process for producing a crystalline mixture solid containingmaltitol, comprising continuously supplying a maltitol aqueous solutioninto an extruder having a slender cooling/kneading zone, kneading whileair is contained in the solution to disperse air bubbles, keepingkneading and cooling the resulting solution to form a maltitol magma andcontinuously extruding the magma.